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Homework Help: Calculate the pressure of the following mixture.

  1. Dec 7, 2011 #1
    1. The problem statement, all variables and given/known data

    An oil reservoir contains at water/oil contact (WOC) of 12000ft contains a water column at 800ft, oil at 500ft and gas at 600ft height

    Calculate the pressure at WOC, 12500, 11700 and 11000 ft?

    2. Relevant equations

    P = rho g h + Patm

    1 ft = 0.305m
    Rho water = 1000
    Rho Oil = 800
    Rho gas = 120

    3. The attempt at a solution

    P WOC = 1000*9.81*(12000*0.305) + 800*9.81*(12000*0.305)+patm = 64.7Mpa

    For the water column for example would the pressure be:

    Pwoc + (1000*9.81*(800*0.305) = 67.1Mpa ?
    or
    Pwoc + (1000*9.81*((12000-800)*0.305)) = 98.2Mpa
    or
    Pwoc+(1000*9.81*((12000+800)*0.305)) = 102.3Mpa

    Basically what height do I have to use?

    And what densitys do I need to use for the depths at 12000, 11700 and 11000ft please?
     
  2. jcsd
  3. Dec 8, 2011 #2
    New approach does this look better?

    Pwoc = (rhoWgh ) + (rhoOgh)
    = (1000*9.8*(12000*0.305)) + (800*9.8*(12000*0.305)
    = 64.6 Mpa

    Pgoc = (rhoG gh) + (rhoO gh)
    = ((120*9.8*((12000-800)*0.305))) + (800*9.8*((12000-800)*0.305)))
    = 30.8 Mpa

    P12500 = (rhoW gh)
    = 1000*9.8*(12500*0.305)
    = 34.7 Mpa
     
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